Ribbon cartridge for a printer

ABSTRACT

A ribbon cartridge for a printer is disclosed which is low in production cost and which is applicable to various kinds of ribbons including one-time ribbons and multiuse ribbons, and in which loadability of the ribbon cartridge in a printer is improved, and in which it is easy to remedy slack in the printing portion of a ribbon. The ribbon cartridge includes a cartridge casing housing therein a ribbon-feeding member and a ribbon-winding member with a printing ribbon entrained therebetween, the cartridge casing having a lid member detachably secured thereto. A projectionless ribbon-feeding roller is rotatably mounted on the cartridge casing and has its outer periphery formed of a high friction material such as rubber. The ribbon-feeding roller is adapted to be housed in the cartridge casing with a part thereof exposed outwardly of the cartridge casing. The ribbon-feeding roller is detachably supported by the cartridge casing and placed in pressure engagement with the winding side of the ribbon wound around the ribbon-winding member.

This application is a continuation of application Ser. No. 907,836,filed Sept. 16, 1986, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a ribbon cartridge for a printer such as, forexample, a thermal printer particularly adapted to be connected with anelectronic computer for printing out the output thereof.

2. Description of the Prior Art

In general, many ink ribbon cartridges (referred to as ribbon cartridgeshereinafter) for thermal-transfer serial printers of the line-sequentialtype and the ribbon-feeding mechanisms for such ribbon cartridgesbasically resemble compact audio tape cartridges and tape-feedingmechanisms for such audio cartridges, respectively. Specifically, such aribbon-feeding mechanism includes a capstan and a pinch roller forfeeding a ribbon at a constant speed or quantity, a friction clutchmechanism mounted on a shaft for a winding spool for transmitting aconstant winding torque from a drive source to the winding spool shaftat all times so that the quantity of the ribbon wound around the shaftis adjusted at a constant level irrespective of the changing effectivediameter of the ribbon wound around the winding spool. However, theribbon-feeding mechanism of this type is disadvantageous in that it iscomplicated in construction and expensive to produce.

In order to eliminate the above-mentioned disadvantages, a proposal hasbeen made for the system illustrated in FIG. 5. In this Figure, theribbon-feeding mechanism as illustrated includes a ribbon-feeding roller1, a winding side 2A of a ribbon, a coiled torsion spring 3 adapted toplace the winding side 2A of the ribbon into pressure engagement withthe ribbon-feeding roller 1, a feeding side 4 of the ribbon, a printingportion 5 of the ribbon extending from the feeding side 4 to the windingside 2A, a ribbon cartridge casing 6 receiving therein theabove-described component members except for the ribbon-feeding roller1, a printing head 7, a ribbon guide 8, a platen 9, and a printing paper10 wound around the platen 9. Besides the above component members, thereare housed in the ribbon cartridge casing 6 a tension mechanism (notshown) for applying a tension of a constant value to the printingportion 5 of the ribbon, and a brake mechanism (not shown) forpreventing unnecessary rotation of the feeding-side ribbon 4 so as toavoid wasteful ribbon feed.

With the above construction, the printing portion 5 of the ribbon ismounted on the printing head 7 and the ribbon guide 8 in the manner asshown in FIG. 5 so that when the printing head 7 is placed by a printingcommand into pressure engagement with the printing paper 10, theprinting portion 5 of the ribbon is intermediate the head and paper.Thereafter, the printing head 7 and the ribbon guide 8 are moved fromthe left to the right in FIG. 5 with their relative positions remainingunchanged, whereby the ink on the printing portion 5 of the ribbon istransferred to the printing paper 10, thus printing letters thereon.Upon completion of printing on the paper 10, the movement of theprinting head 7 and the ribbon guide 8 is stopped and the printing head7 and the printing portion 5 of the ribbon are moved away from the theprinting paper 10. Then, the printing paper 10 is fed at a predeterminedamount by rotation of the platen 9 so as to bring up a new printingline.

Subsequently, the printing head 7 and the ribbon guide 8 are moved fromthe right to the left in FIG. 5 to return to their initial positions,and simultaneously with this return movement, the ribbon-feeding roller1 is caused to rotate in the counterclockwise direction in FIG. 5 sothat the winding side 2A of the ribbon, being placed in pressureengagement with the ribbon-feeding roller 1 under the action of thecoiled torsion spring 3, is forced to rotate in the clockwise directionin FIG. 5 thereby to move the printing portion 5 of the ribbon from theright to the left in FIG. 5 for winding thereof. The printing head 7 andthe ribbon guide 8 are returned to their next print-starting positionsand stopped there. Simultaneously with this, the rotation of theribbon-feeding roller 1 is also stopped and the printing operation onone line is thus completed. Thereafter, the above-described operationsare repeated by means of a printing command, and the amount of thewinding side 2A of the ribbon wound increases accordingly up to afully-wound condition indicted by the dotted line 2B in FIG. 5.

In the above-described operations, the reciprocating movement of theprinting head 7 and the winding of the ribbon can be effected by asingle drive source such as, for example, a stepping motor, i.e. by theforward or reverse rotation of the motor. Specifically, during printingoperation, the winding of the ribbon is interrupted under the action ofa one-way clutch (not shown), and during the return stroke, the returnof the printing head 7 and the winding of the ribbon can be concurrentlyeffected. Of course, these operations may also be made by respectiveindependent drive sources.

The thermal printing ribbon is a one-time ribbon and hence it isrequired that the above-described winding amount of the ribbon begreater than the returning amount of the printing head 7 so that a usedportion of the ribbon is not placed in a printing portion again. In thisconnection, the above-mentioned conventional ribbon cartridge has amajor feature in that such a requirement can be met by taking intoaccount only the angle of rotation of the ribbon-feeding roller 1irrespective of the diameter of the wound ribbon 2A.

In the conventional ribbon-feeding mechanism of the above kind, theribbon-feeding roller 1 employed comprises a toothed roller which isformed of a metal disc about 0.2 to 0.5 mm thick and having saw teethformed in its outer peripheral portion, as illustrated in FIG. 5.Otherwise, the ribbon-feeding roller 1 may comprise a shaft having aplurality of short pins implanted radially on its outer peripheralsurface. In either case, productivity is low and the cost ofmanufacturing becomes high.

Further, when the ribbon cartridge is not in use or is not loaded in aprinter, the winding side 2A of the ribbon 2A is displaced by thetorsion spring 3 toward the position indicated by the dotted line 2Cwherein the ribbon 2A abuts against the peripheral wall of the cartridgecasing 6. For loading of the cartridge in a printer, the ribbon-feedingroller 1 is moved away from its operating position shown in FIG. 5 in adirection indicated by an arrow and then the ribbon cartridge is loadedin the printer from above, or the ribbon cartridge is slid laterally andset in place in the printer, or the winding side of the ribbon displacedto the dotted-line position 2C is first slid toward the full-lineposition 2A and then the ribbon cartridge is loaded in the printer fromabove. Accordingly, in either case, the cartridge loading operation isvery cumbersome.

Further, in cases where the printing portion 5 of the ribbon is slack inthe free or non-loaded state thereof, it is difficult to turn thewinding-side ribbon 2A for removal of such slack since the ribbon 2C isplaced in frictional contact with the peripheral wall of the cartridgecasing 6 under the bias of the torsion spring 3. As a result, it ispreferable to turn the feeding side 4 of the ribbon in the rewindingdirection and to this end, provision is needed for a knob by means ofwhich the ribbon 4 can be turned. If, however, the printing portion 5 ofthe ribbon is damaged, rewinding of the feeding side 4 of the ribbon cannot remove or remedy such damage, thus resulting in printing troubles.

On the other hand, although almost all thermal printing ribbons now ingeneral use are one-time ribbons, it is expected in the near future thata multiuse or extended use ribbon reusable ten times or so will bedeveloped and reduced to practice. In such a multiuse ribbon, thewinding amount of the ribbon need not be greater than the return strokeof the printing head 7, and the ratio of the ribbon-winding amount tothe printing head return stroke can be determined in accordance with thenumber of usable times required. However, this results in a change inrotation angle of the ribbon-feeding roller 1 and it is impossible toeconomically use the above-described two kinds of ribbons with the sameprinter.

Thus, the conventional ribbon cartridge for a printer as described aboveinvolves various disadvantages. Namely, the ribbon-feeding roller iscostly and less productive; loading of the ribbon cartridge in a printeris troublesome and inefficient; slack in the printing ribbon can not bereadily removed or remedied; and the ribbon cartridge has nosatisfactory application with an extended use ribbon for the reasondiscussed immediately above and because of ribbon-feeding rollers of thetype shown in FIG. 5 having projections on their outer peripheries.

SUMMARY OF THE INVENTION

Accordingly, the present invention is intended to obviate theabove-described various disadvantages of the prior art, and has for itsobject the provision of a ribbon cartridge for a printer which is low inproduction cost and is applicable to various kinds of ribbons includingone-time ribbons and multiuse ribbons, and in which loadability of theribbon cartridge in a printer is improved, and in which it is easy toremedy slack in the printing portion of a ribbon.

In order to achieve the above object, according to the presentinvention, there is provided a ribbon cartridge for a printer whichcomprises:

a ribbon cartridge casing housing therein a ribbon-feeding means and aribbon-winding means with a printing ribbon entrained therebetween, thecartridge casing having a lid member detachably secured thereto; and

a ribbon-feeding roller having a projectionless outer periphery formedof a high friction material and adapted to be housed in the cartridgecasing with a part thereof exposed outwardly of the cartridge casing,the ribbon-feeding roller being detachably supported by the cartridgecasing and being placed in pressure engagement with the winding side ofthe ribbon wound around the ribbon-winding means.

It is preferred that the ribbon-feeding roller comprise a sleevesupported by the ribbon cartridge casing and releasably engageable witha drive shaft of a printer, and a roller member formed of the highfriction material and fixedly mounted on the outer peripheral surface ofthe sleeve.

Preferably, the roller member is formed of rubber having a degree ofhardness in the range from Hs 30 to 50 degrees.

The above and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof a presently preferred embodiment of the invention when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing in cross section a general arrangement ofa ribbon cartridge for a printer in accordance with the presentinvention;

FIG. 2 is a front elevational cross section showing essential parts ofthe ribbon cartridge;

FIG. 3 is a a cross sectional view taken along the line III--III in FIG.2;

FIG. 4 is a partial cross sectional view showing a slider slidablymounted on the side wall of a cartridge casing; and

FIG. 5 is a plan view similar to FIG. 1 showing a general arrangement ofa conventional ribbon cartridge for a printer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 through 4 show a presently preferred embodiment of the presentinvention. FIG. 1 is a plan view similar to FIG. 5, showing in crosssection a general arrangement of a ribbon cartridge for a thermalprinter of the present invention. The component parts of the ribboncartridge other than a ribbon-feeding roller 11 illustrated in FIG. 1are similar to those shown in FIG. 5 and identified by the samereference numerals as employed in FIG. 5, and thus any detaileddescription of the same component parts as in FIG. 5 will beunnecessary.

According to the present invention, the ribbon-feeding roller 11 has itsouter periphery formed of a high friction material such as rubber havinga low degree of hardness, and is housed in a ribbon cartridge casing 6together with a winding side 2A of a ribbon, a feeding side 4 of theribbon and a printing portion 5 of the ribbon.

As pictured in detail in FIG. 2, the ribbon-feeding roller 11 comprisesa roller member 11A formed of a high friction material such as rubberand a sleeve 11B firmly mounting thereon the roller member 11A, thesleeve 11B being freely rotatably supported at its opposite ends by thecartridge casing 6 and a lid member 6A, respectively. The lid member 6Ais detachably secured to the casing 6.

A drive shaft 13 is rotatably supported by a base 14 of a printer and isadapted to be inserted into the sleeve 11B for driving thereof. Asclearly seen from FIG. 3, the drive shaft 13 is formed on its outerperipheral surface with a plurality of axially extending teeth which,when inserted into the sleeve 11B, are in meshing engagement with aplurality of corresponding axially extending teeth formed in the innerperipheral surface of the sleeve 11B for integral rotation therewith. Inthis manner, the drive shaft 13 is releasably engageable with the sleeve11B.

As shown in FIG. 2, the winding side 2A of the ribbon has a core 2Dwhich is rotatably mounted on a support pin 12a fixedly secured to aslider 12 which is attached to the side wall of the cartridge casing 6for sliding movement relative thereto in a direction toward and awayfrom the ribbon-feeding roller 11, as depicted in detail in FIG. 4. Theslider 12 is biased by means of a coiled torsion spring 3 in a directiontoward the ribbon-feeding roller 11 whereby the winding side 2A of theribbon is placed into pressure engagement with the roller member 11A.

In this connection, it is to be noted that the roller member 11A isformed of rubber of a low degree of hardness, for example, in the rangefrom Hs 30 to 50 degrees, so that there will be created a satisfactoryfrictional force between the ribbon and the roller. As illustrated inFIGS. 1 and 2, a part of the roller member 11A is exposed outwardly ofthe cartridge casing 6.

With the above-described arrangement, the drive shaft 13 rotatablysupported by the base 14 of the thermal printer is driven to rotate inthe counterclockwise direction in FIG. 1 during the returning stroke ofthe printing head 7 so that the ribbon-feeding roller 11, being inmeshing engagement with the drive shaft 13, is likewise caused by thedrive shaft 13 to rotate in the counterclockwise direction, thuseffecting a ribbon winding operation similar to that in the conventionalribbon cartridge illustrated in FIG. 5.

Further, when the ribbon cartridge is in a free or non-loaded condition,an operator can directly turn the ribbon-feeding roller 11 so as to windthe winding side 2A of the ribbon, thus removing any slack in theprinting portion 5 of the ribbon without difficulty. In addition, it iseasy to load the ribbon cartridge in a printer since there is no needfor the ribbon-feeding roller 11 to be pushed in the cartridge casing.Also, it is possible to replace a worn-out ribbon-feeding roller with anew one simply by removing the lid member 6A from the cartridge casing6.

As described in the foregoing, according to the present invention, theribbon-feeding roller is formed of rubber and housed in the cartridgecasing with a portion thereof exposed outwardly of the cartridge casing,and the lid member can be detachably secured to the cartridge casing.With this arrangement, the ribbon-feeding roller can be produced at lowcost, and it is easy not only to load the ribbon cartridge in a printerbut also to remedy or remove any slack of the ribbon. Moreover, due tothe fact that it is possible to effect replacement of the ribbon-feedingroller, a one-time ribbon can be replaced with a multiuse ribbon so thatthe multiuse ribbon can be used with the same printer.

It will be readily understood to the skilled in the art that althoughthe above description has been made of a ribbon cartridge for a thermalprinter, the principles of the present invention will be similarlyapplicable to a ribbon cartridge for printers of general purposes.

What is claimed is:
 1. A ribbon cartridge for a printer comprising:aribbon cartridge casing housing therein a ribbon-feeding means and aribbon-winding means with a printing ribbon entrained therebetween, saidcartridge casing having means for enabling replacement of the contentsof said cartridge comprising a detachable and replaceable lid member; aribbon-feeding roller having a projectionless outer periphery formed ofa high friction rubber material and, said ribbon-feeding roller beingdetachably and replaceably mounted in said cartridge casing, part of theribbon-feeding roller being exposed outwardly of said cartridge casingand part of said ribbon-feeding roller being in pressure engagement withthe winding side of the ribbon wound around said ribbon-winding means.2. A ribbon cartridge for a printer as claimed in claim 1, wherein saidribbon-feeding roller comprises a sleeve supported by said ribboncartridge casing and being releasably engageable with a coaxiallyarranged drive shaft of a printer, and a roller member formed of thehigh friction material and fixedly mounted on the outer peripheralsurface of said sleeve.
 3. A ribbon cartridge for a printer as claimedin claim 2, wherein said roller member is formed of rubber having adegree of hardness in the range from Hs 30 to 50 degrees.
 4. A ribboncartridge for a printer as claimed in claim 1 wherein saidribbon-feeding means and said ribbon-winding means are in spacedrelationship.